What is the UID cookie?
A third-party identifier cookie used by Comscore (ScorecardResearch) for cross-site audience measurement and market research.
Table of Contents
About the UID cookie
| Vendor | Comscore |
|---|---|
| Cookie Domain | scorecardresearch.com |
| Category Category The functional category of the technology, such as Web Analytics or Social Media. Learn more | Audience Research & Feedback |
| Consent Category Consent Category The consent category this cookie most commonly falls under across sites we scan, normalized into four standard categories. Learn more | Targeting & Advertising |
| Prevalence | Very Common |
| Popularity Popularity Popularity is calculated from our dataset of 4.5B+ cookies analyzed across hundreds of millions of web pages. Learn more | Found on 10.1% of scanned pages |
| Expiration Type | Timestamp |
| Expiration Duration | 24 days |
| Party Type Party Type Whether the cookie is first-party or third-party. Learn more | 3rd-Party |
| Risk Level Risk Level Rates how sensitive the data stored by this cookie is (High, Medium, or Low) based on data classification and distribution. Learn more | Medium |
| Vendor Privacy Policy | https://www.comscore.com/About/Privacy-Policy |
| Vendor Website | https://www.comscore.com/ |
What is the purpose of the UID cookie?
The UID cookie is a persistent third-party tracker set by Comscore's ScorecardResearch tags (e.g., comScore Website Tag, comScore Video Metrix). Its primary function is to assign a unique, pseudonymous identifier to the user's browser, which is then used to track online activities, media consumption, and website visitation across any site where the tag is installed.
This tracking generates broad consumer behavioral profiles, enabling Comscore to measure cross-site traffic, evaluate audience demographics, calculate reach and frequency for advertising campaigns, and provide actionable analytics and market research reports to website owners and media buyers.
What are the Privacy Risks of the UID cookie?
Risk Level: Medium
The UID cookie captures detailed pseudonymous browsing behavior across multiple, independent publisher domains. While Comscore states it does not directly collect personally identifiable information (PII) such as names or emails through this cookie, the unique 32-character identifier allows for the extensive profiling of consumer preferences, long-term cross-site tracking, and device fingerprinting. This presents a moderate privacy risk due to the scale of tracking and its application in behavioral modeling and audience measurement.
How to Remove the UID cookie from a Website
Because this cookie is set directly by the ScorecardResearch (Comscore) web tags, a site administrator must remove or disable the Comscore scripts (such as the comScore Website Tag or Video Metrix tag) from their pages to stop the cookie from being dropped. If the scripts are deployed through a tag management system, the corresponding Comscore tags should be removed or disabled there. The cookie is integral to how the ScorecardResearch tag operates, so it cannot be eliminated without removing the Comscore tag/service itself.